Book Image

Advanced Natural Language Processing with TensorFlow 2

By : Ashish Bansal, Tony Mullen
Book Image

Advanced Natural Language Processing with TensorFlow 2

By: Ashish Bansal, Tony Mullen

Overview of this book

Recently, there have been tremendous advances in NLP, and we are now moving from research labs into practical applications. This book comes with a perfect blend of both the theoretical and practical aspects of trending and complex NLP techniques. The book is focused on innovative applications in the field of NLP, language generation, and dialogue systems. It helps you apply the concepts of pre-processing text using techniques such as tokenization, parts of speech tagging, and lemmatization using popular libraries such as Stanford NLP and SpaCy. You will build Named Entity Recognition (NER) from scratch using Conditional Random Fields and Viterbi Decoding on top of RNNs. The book covers key emerging areas such as generating text for use in sentence completion and text summarization, bridging images and text by generating captions for images, and managing dialogue aspects of chatbots. You will learn how to apply transfer learning and fine-tuning using TensorFlow 2. Further, it covers practical techniques that can simplify the labelling of textual data. The book also has a working code that is adaptable to your use cases for each tech piece. By the end of the book, you will have an advanced knowledge of the tools, techniques and deep learning architecture used to solve complex NLP problems.
Table of Contents (13 chapters)
11
Other Books You May Enjoy
12
Index

Conditional random fields (CRFs)

BiLSTM models look at a sequence of input words and predict the label for the current word. In making this determination, only the information of previous inputs is considered. Previous predictions play no role in making this decision. However, there is information encoded in the sequence of labels that is being discounted. To illustrate this point, consider a subset of NER tags: O, B-Per, I-Per, B-Geo, and I-Geo. This represents two domains of person and geographical entities and an Other category for everything else. Based on the structure of IOB tags, we know that any I- tag must be preceded by a B-I from the same domain. This also implies that an I- tag cannot be preceded by an O tag. The following diagram shows the possible state transitions between these tags:

Figure 3.2: Possible NER tag transitions

Figure 3.2 color codes similar types of transitions with the same color. An O tag can transition only to a B tag...